semaphore.h

/*****************************************************/
/* lean Concurrent              (c) Tobias Zirr 2011 */
/*****************************************************/

#ifndef LEAN_CONCURRENT_SEMAPHORE
#define LEAN_CONCURRENT_SEMAPHORE

#include "../lean.h"
#include "../tags/noncopyable.h"
#include <windows.h>

namespace lean
{
namespace concurrent
{

class semaphore : public noncopyable
{
private:
    HANDLE m_semaphore;

public:
    explicit semaphore(long initialCount = 1)
        : m_semaphore( ::CreateSemaphoreW(NULL, initialCount, LONG_MAX, NULL) )
    {
        LEAN_ASSERT(m_semaphore != NULL);
    }
    ~semaphore()
    {
        ::CloseHandle(m_semaphore);
    }

    LEAN_INLINE bool try_lock()
    {
        return (::WaitForSingleObject(m_semaphore, 0) == WAIT_OBJECT_0);
    }

    LEAN_INLINE void lock()
    {
        DWORD result = ::WaitForSingleObject(m_semaphore, INFINITE);
        LEAN_ASSERT(result == WAIT_OBJECT_0);
    }

    LEAN_INLINE void unlock()
    {
        BOOL result = ::ReleaseSemaphore(m_semaphore, 1, NULL);
        LEAN_ASSERT(result != FALSE);
    }

    LEAN_INLINE HANDLE native_handle() const
    {
        return m_semaphore;
    }
};

} // namespace

using concurrent::semaphore;

} // namespace

#endif